Conventional optical semiconductor devices including an optical semiconductor element mounted therein, for example, have a configuration including a metallic lead frame 1, an optical semiconductor element 2 mounted thereon, and a resin wall formed from a resin layer 3 so as to surround the circumference of the optical semiconductor element 2, as shown in FIG. 1a. In FIG. 1a, numeral 4 denotes a bonding wire which electrically connects an electrode circuit (not shown) formed on the metallic lead frame 1 to the optical semiconductor element 2, the bonding wire being disposed according to need.
When such an optical semiconductor device is produced, the resin layer 3 is formed by the injection molding of a thermoplastic resin represented by a polyimide resin (PPA) or the like. A white pigment is generally incorporated into the thermoplastic resin to reflect the light emitted by the optical semiconductor element 2 and impart directivity thereto (see patent document 1).
On the other hand, in the case where high heat resistance is required, a ceramic material containing sintered alumina is mainly used to form a part in place of the resin layer 3 (see patent document 2).
However, the formation of the part corresponding to the resin layer 3 from the ceramic material is problematic in view of the suitability for mass production and cost of such packages, etc. Because of this, the resin layer 3 is generally formed using the thermoplastic resin.
Patent Document 1: JP-A-2002-283498
Patent Document 2: JP-A-2002-232017